> I would like to simplify some expressions involving Bessel
> functions using recurrences relationships like
>
> bessel_j(nu-1,z)+bessel_j(nu+1,z) = 2/nu * bessel_j(nu,z)
> bessel_y(nu-1,z)+bessel_y(nu+1,z) = 2/nu * bessel_y(nu,z)
Could you give some examples of the expressions you're starting with and
how you'd like to use these relations to simplify them?